Fauché comme les blés

Literally: Mown like the wheat

Example: “À la fin du mois, les étudiants sont fauchés comme les blés.” — By the end of the month, the students are flat broke.

English equivalent: Flat broke

Origin: Faucher is to cut with a scythe, and a mown field is left stripped level with nothing standing — which is the state of the wallet in question. Gaston Esnault dates fauché in this sense to 1877; the comme les blés extension follows in 1899. There is a pun buried in it, because blé is also slang for money, so the mown wheat and the missing cash are the same joke. And the older sense of the verb ties the two together: in the 17th century, when purses still hung from the belt, a thief mowed when he cut one loose — leaving the man he mowed without a sou, and so, in the other sense, fauché.